Fig. 1. Purification of a HIM from Drosophila embryo extracts. (A) Purification scheme for the purification of myc-tagged SU(VAR)3-9 from Drosophila embryonal extracts. (B) Purification of myc-SU(VAR)3-9 from nuclear extracts prepared from flies expressing a myc-tagged SU(VAR)3-9 (Aagaard, 1999) on a resource Q column. Western blot of fractions eluted from the resource Q column probed with an anti-c-myc antibody (9E10). (C) HIM activity assay with immunoprecipitates of SU(VAR)3-9 from an extract (myc-NE) or from partially purified myc-SU(VAR)3-9 fractions (fraction 26) prepared from flies expressing triple-myc-tagged SU(VAR)3-9 using an anti-myc antibody (9E10). As controls immunoprecipitations were also performed without the addition of antibody (mock) or from an extract prepared from wild-type embryos (wt).